Mittenothamnium, as presently recognized, is similar to Chryso-hypnum but differs in having a primary stipe-like stem, lanceolate pseudoparaphyllia, and leaf cells usually projecting only at distal angles. Chryso-hypnum segregated from Mittenothamnium, is poorly known. In both genera there are an inflated number of species described mostly from the Neotropics, and less so from Africa and associated islands. There may be only 5-10 species. The genus was previously placed in Mittenothamnium, and earlier in Microthamnium and Stereohypnum. Keys adapted from Nishimura and Ando (in Sharp et al. 1994).